Textbook-Integrated Guide to Educational Resources

TIGER

Separation Anxiety: An In-Class Game Designed To Help Students Discover ChromatographyMichael J. SamideAn in-class activity, designed on the basis of plate theory, allows students to physically separate coins on the basis of a provided partition coefficient. Students move coins between stationary and mobile phases to establish equilibrium conditions. The goal is to have students understand equilibration as it relates to separation, which can lead into a discussion of more complex topics.Samide, Michael J. J. Chem. Educ.2008, 85, 1512.

An Updated Equilibrium MachineEmeric SchultzDescribes a device that can demonstrate equilibrium and the Le Châtelier principle, as well as kinetic and thermodynamic concepts. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when various air pressures are applied by the blower.Schultz, Emeric. J. Chem. Educ.2008, 85, 1131.

EQVAPSIM: A Vapor–Liquid Equilibria of Binary Systems Computer Simulation by LabVIEWA. Belletti, R. Borromei, and G. InglettoReports the results of a program using LabVIEW software to simulate the construction of a phase diagram representing a liquidvapor equilibrium. The program models work in a real laboratory, including mistakes commonly made in this context.Belletti, A.; Borromei, R.; Ingletto, G. J. Chem. Educ.2008, 85, 879.

Determining the Solubility Product of Fe(OH)3: An Equilibrium Study with Environmental SignificanceMichelle Meighan, Joseph MacNeil, and Renee FalconerThis study explores the environmental impact of acidic mine drainage by investigating the relationship between pH and the aqueous solubility of heavy metals. Students precipitate Fe(OH)3 from acidic FeCl3 and NaOH and use the concentrations of ferric and hydroxide ionsdetermined through pH and flame spectroscopyto calculate the Ksp of Fe(OH)3.Meighan, Michelle; MacNeil, Joseph; Falconer, Renee. J. Chem. Educ.2008, 85, 254.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Precipitation / Solubility |

Spectroscopy

Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry LaboratoryKristen L. Cacciatore, Jose Amado, Jason J. Evans, and Hannah SevianPresents a novel first-year chemistry experiment that asks students to replicate procedures described in sample lab reports that lack essential information. This structure is designed to promote students' experimental design and data analysis skills as well as their understanding of the importance and essential qualities of written and verbal communication between scientists.Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah. J. Chem. Educ.2008, 85, 251.

Equilibrium |

Green Chemistry |

Periodicity / Periodic Table |

Solutions / Solvents |

Stoichiometry |

Titration / Volumetric Analysis

A Simplified Model To Predict the Effect of Increasing Atmospheric CO2 on Carbonate Chemistry in the OceanBrian J. Bozlee, Maria Janebo, and Ginger JahnThe chemistry of dissolved inorganic carbon in seawater is reviewed and used to predict the potential effect of rising levels of carbon dioxide in the atmosphere. It is found that calcium carbonate may become unsaturated in cold surface seawater by the year 2100, resulting in the destruction of calcifying organisms such as coral.Bozlee, Brian J.; Janebo, Maria; Jahn, Ginger. J. Chem. Educ.2008, 85, 213.

Using the Science Writing Heuristic To Improve Students' Understanding of General EquilibriumJames A. Rudd, II, Thomas J. Greenbowe, and Brian M. HandThis study examines the performance of students using the Science Writing Heuristic approach, which facilitates scientific inquiry by structuring the laboratory notebook in a format that guides students to answer directed questions, on lecture exams and a laboratory practical exam on chemical equilibrium.Rudd, James A., II; Greenbowe, Thomas J.; Hand, Brian M. J. Chem. Educ.2007, 84, 2007.

Equilibrium |

Learning Theories |

TA Training / Orientation |

Student-Centered Learning

The Use of Limits in an Advanced Placement Chemistry CoursePaul S. Matsumoto, Jonathan Ring, and Jia Li (Lily) ZhuThis article describes the use of limits in topics usually covered in advanced placement or first-year college chemistry. This approach supplements the interpretation of the graph of an equation since it is usually easier to evaluate the limit of a function than to generate its graph.Matsumoto, Paul S.; Ring, Jonathan; Zhu, Jia Li (Lily). J. Chem. Educ.2007, 84, 1655.

Exception to the Le Châtelier PrincipleDavid S. Corti and Mark J. UlineDisagreement regarding an apparent exception to the Le Chtelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Corti, David S.; Uline, Mark J. J. Chem. Educ.2007, 84, 1427.

Equilibrium

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chtelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Equilibrium |

Gases

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chatelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Equilibrium |

Gases

Peer-Developed and Peer-Led Labs in General ChemistryLorena Tribe and Kim KostkaDescribes a student-developed and led laboratory curriculum as a model for producing a more student-centered and rich laboratory experience in general chemistry laboratories.Tribe, Lorena; Kostka, Kim. J. Chem. Educ.2007, 84, 1031.

Teaching Physical Chemistry Experiments with a Computer Simulation by LabVIEWA. Belletti, R. Borromei, and G. InglettoThis article reports on a computer simulation developed with the software LabVIEW of the physical chemistry experiment regarding the vapor pressure measurements of a pure liquid as a function of temperature, as well as a system of data collecting that emphasizes the similarities between the virtual and real experiment.Belletti, A.; Borromei, R.; Ingletto, G. J. Chem. Educ.2006, 83, 1353.

Equilibrium |

Laboratory Computing / Interfacing |

Liquids |

Thermodynamics |

Gases |

Student-Centered Learning

Equilibrium Constants and Water Activity RevisitedDavid KeeportsSubtle arguments based upon the use of chemical potentials show that numerical values of solute molar concentrations can be used as good approximate activities in equilibrium calculations for reactions involving dilute solutions.Keeports, David. J. Chem. Educ.2006, 83, 1290.

A New Java Animation in Peer-Reviewed JCE WebWareWilliam F. Coleman and Edward W. FedoskyJust added to JCE WebWare, Computer Simulations of Salt Solubility uses a Java applet and Web browser to present an animated illustration of differences in the solubility of salts due to differences in the entropy of solvation.Coleman, William F.; Fedosky, Edward W. J. Chem. Educ.2006, 83, 173.

Equilibria That Shift Left upon Addition of More ReactantJeffrey E. LacyMost textbook presentations of Le Chtelier's principle in general and physical chemistry do not include a discussion of constant pressure conditions for which addition of a reactant can shift the equilibrium to the left. We propose presentations of isothermal, open systems at constant pressure for both levels of study by using concepts and skills that the respective students already possess. In addition, we derive novel criteria based on the stoichiometry of the reaction that can be used to identify those equilibria that will shift left upon addition of more reactant. Lacy, Jeffrey E. J. Chem. Educ.2005, 82, 1192.

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoWhile my paper states that the reaction quotient (Q) is not needed to solve equilibrium problems, it does not imply that Q is not valuable. In fact, when I teach this topic to my AP chemistry class, I initially use Q to solve the problem, then mention the alternative method described in the paper.Matsumoto, Paul S. J. Chem. Educ.2005, 82, 1150.

Equilibrium |

Learning Theories |

Mathematics / Symbolic Mathematics

The Reaction Quotient Is Unnecessary To Solve Equilibrium Problems: No Problems with QRobert LedererMr. Matsumotos students are to be congratulated for discerning an interesting mathematical procedure. Exclusively utilizing this algorithm, however, short-cuts the understanding of the chemistry involved. Students of chemistry should be challenged to understand why something occurs, and not to be satisfied with how to perform the often mundane calculations.Lederer, Robert. J. Chem. Educ.2005, 82, 1149.

Equilibrium Constants and Water ActivityDavid KeeportsGeneral chemistry instructors are faced with a dilemma when introducing the topic of equilibrium constants: These constants are correctly written in terms of activities, yet activity is a complex topic better treated rigorously in a physical chemistry course than superficially in a general chemistry course. Thus, to introduce equilibrium calculations, it is necessary to use approximate forms for equilibrium constants. However, I find that some commonly used textbooks provide incorrect arguments leading to approximate equilibrium constants for aqueous reactions.Keeports, David. J. Chem. Educ.2005, 82, 999.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Water / Water Chemistry

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of StateCubic equations of state are widely used by chemists and chemical engineers to predict the thermodynamic properties of both pure substances and mixtures. In particular, these equations enable predictions concerning the temperature and pressure at which vaporliquid equilibrium occurs. These two educational JavaScript programs perform calculations using cubic equations of state and, equally importantly, explain how the calculations are performed.J. Chem. Educ.2005, 82, 960.

Enrichment / Review Materials |

Equilibrium |

Thermodynamics

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of StatePatrick J. BarrieIn this article, two JavaScript programs are described. The first program gives students the choice of five different cubic equations of state and performs calculations for pure substances. The second program predicts vaporliquid equilibrium for binary mixtures using a choice of three modern equations of state and the van der Waals mixing rules.Barrie, Patrick J. J. Chem. Educ.2005, 82, 958.

Enrichment / Review Materials |

Thermodynamics |

Equilibrium

Procedure for Decomposing a Redox Reaction into Half-ReactionsIlie Fishtik and Ladislav H. BerkaThe principle of stoichiometric uniqueness provides a simple algorithm to check whether a simple redox reaction may be uniquely decomposed into half-reactions in a single way. For complex redox reactions the approach permits a complete enumeration of a finite and unique number of ways a redox reaction may be decomposed into half-reactions. Several examples are given. Fishtik, Ilie; Berka, Ladislav H. J. Chem. Educ.2005, 82, 553.

Stoichiometry |

Equilibrium |

Electrochemistry |

Oxidation / Reduction |

Reactions |

Thermodynamics

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoThe traditional method to determine the equilibrium concentration of chemicals in a reaction, given the equilibrium constant and the initial concentration of chemicals in the reaction, involves the determination of the reaction quotient. This article will demonstrate that this step may be eliminated; thereby simplifying the algorithm to solve such problems. Such a reduction in the complexity of the algorithm may result in more students successfully being able to solve such problems. Matsumoto, Paul S. J. Chem. Educ.2005, 82, 406.

Equilibrium |

Learning Theories |

Chemometrics

Putting A Human Face on EquilibriumNeil GlicksteinA short biography of chemist Fritz Haber is used to personalize the abstract concepts of equilibrium chemistry for high school students in an introductory course. In addition to giving the HaberBosch process an historic, an economic, and a scientific background the reading and subsequent discussion allows students for whom the human perspective is of paramount importance a chance to investigate the irony of balance or equilibrium in Haber's life story.Glickstein, Neil. J. Chem. Educ.2005, 82, 391.

Equilibrium

Analysis of Natural Buffer Systems and the Impact of Acid Rain. An Environmental Project for First-Year Chemistry StudentsDavid C. Powers, Andrew T. Higgs, Matt L. Obley, Phyllis A. Leber, Kenneth R. Hess, and Claude H. YoderThe purpose of this project is to investigate the basic principles involved in acidbase buffer systems within the context of an environmental issue. It is designed for use in an introductory chemistry course. The students will learn about acidbase interactions and examine how a buffer system composed of a weak acid and its conjugate base can neutralize large quantities of strong acid while resisting drastic change in the pH of the system. Students will also analyze experimentally the various components of the most commonly occurring natural buffer system.Powers, David C.; Higgs, Andrew T.; Obley, Matt L.; Leber, Phyllis A.; Hess, Kenneth R.; Yoder, Claude H. J. Chem. Educ.2005, 82, 274.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Playing Card EquilibriumFrank L. LambertFrom experience, I am hypersensitive to the misconceptions of students and instructors that can be caused when playing cards are used in teaching chemistry. The root of such errors lies in overlooking the non-mobile, non-energetically-interacting nature of pieces of cardboard. Only if they are being shuffled can cards serve as some sort of analogy to molecular behavior in chemistry.Lambert, Frank L. J. Chem. Educ.2004, 81, 1569.

Equilibrium |

Statistical Mechanics |

Thermodynamics

Unified Approximations: A New Approach for Monoprotic Weak Acid–Base EquilibriaHarry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. TesfaiThis article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero. Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ.2004, 81, 1367.

Acids / Bases |

Equilibrium |

Chemometrics

Reaction to Why Do We Teach Equilibrium Calculations?Stephen J. Hawkes"Rigor" in introductory chemistry is often equated with quantitation. Consequently the understanding of chemical reactions and properties is obscured. This was illustrated by Stumpo who asked students to calculate ?E of a reaction, and then on another question on the same test asked a question aimed at its meaning. 77% of the students calculated correctly, but only 24% showed understanding of its meaning. The ability to calculate a number does not measure understanding of the number. Hawkes, Stephen J. J. Chem. Educ.2004, 81, 1265.

Equilibrium |

Chemometrics

Reaction to Why Do We Teach Equilibrium Calculations? Don L. LewisA recently published correspondence by Stephen J. Hawkes on teaching equilibrium calculations troubles me. Hawkes dismisses equilibrium calculations as mere algorithms, best deferred until the student can use computer programs. I find it difficult to believe that a computer program enhances understanding. From a chemists point of view, the equilibrium condition is a limit, a limit that (because of stochastic considerations) does not exist. It might be better to make the reaction quotient statement using < or > but the use of those relations is delayed until quantum mechanics.Lewis, Don L. J. Chem. Educ.2004, 81, 1265.

Equilibrium |

Chemometrics

Why Do We Teach Equilibrium Calculations?Stephen J. HawkesIs there any substantial value to students in learning these calculations? Is there value enough to warrant inclusion in the one year of introductory chemistry?Hawkes, Stephen J. J. Chem. Educ.2003, 80, 1381.

Equilibrium

Playing-Card EquilibriumRobert M. HansonA simple hands-on simulation suitable for either classroom use or laboratory investigation involves using a standard deck of playing cards to explore the statistical aspects of equilibrium. Concepts that can be easily demonstrated include fluctuation around a most probable distribution, Le Chtelier's principle, the equilibrium constant, prediction of the equilibrium constant based on probability, and the effect of sample size on equilibrium fluctuations. Hanson, Robert M. J. Chem. Educ.2003, 80, 1271.

The Relative Acidities of Water and MethanolHenry I. AbrashAnalysis of the disparity between the way the acidity constant of water is presented in general chemistry and organic chemistry textbooks.Abrash, Henry I. J. Chem. Educ.2001, 78, 1496.

Assessing Students' Conceptual Understanding of Solubility EquilibriumAndrés RavioloA problem about solubility equilibrium is presented as a resource for the evaluation of students; it involves macroscopic, microscopic, and symbolic levels of representation, and allows one to assess whether students have acquired an adequate conceptual understanding of the phenomenon.Raviolo, Andrés. J. Chem. Educ.2001, 78, 629.

Kinetic-Molecular Theory |

Equilibrium |

Precipitation / Solubility

Are Fizzing Drinks Boiling? A Chemical Insight from Chemical Education ResearchAlan GoodwinThe suggestion that fizzing drinks are examples of liquids boiling at room temperature has proved to be controversial among both chemists and chemical educators. This paper presents a case for believing this everyday system to be a good example of a boiling solution and the consequent separation of carbon dioxide from the solution to exemplify fractional distillation. Goodwin, Alan. J. Chem. Educ.2001, 78, 385.

Aqueous Solution Chemistry |

Kinetic-Molecular Theory |

Equilibrium |

Gases |

Solutions / Solvents |

Phases / Phase Transitions / Diagrams

The State of Division of Solids and Chemical EquilibriaJoão C. M. Paiva and Victor M. S. GilAn experiment and a computer simulation are presented to address a counterintuitive situation often encountered when teaching chemical equilibria. This is prompted by the question "How can the subdivision of a solid reactant affect the reaction rate and not the composition of the equilibrium state?" Paiva, João C. M.; Gil, Victor M. S. J. Chem. Educ.2001, 78, 222.

Modification of Small-Scale One-Pot Reactions to an Inquiry-Based Laboratory ExerciseC. Jayne WilcoxStudents are given an initial handout and asked to complete a short, attention-getting exercise. They must continue to work on logical, short exercises given to them one at a time, in handout format. The inquiry-based approach is intended to increase students' comprehension of what they're doing in the laboratory and why.Wilcox, C. Jayne. J. Chem. Educ.2001, 78, 62.

Are We Taking Symbolic Language for Granted? Paul Marais and Faan JordaanThis study formed part of a broader investigation into the role of language in teaching and learning chemical equilibrium. Students were tested for their understanding of 25 words and five symbols commonly used in connection with chemical equilibrium. This test showed that most of the students had an inadequate grasp of the meaning of all five symbols. It also showed that, on the average, their understanding of symbols was more problematic than their understanding of words.Marais, Paul; Jordaan, Faan. J. Chem. Educ.2000, 77, 1355.

Simulating Dynamic Equilibria: A Class ExperimentJohn A. Harrison and Paul D. BuckleyA first-order reversible reaction is simulated on an overhead projector using small coins or discs. Results illustrate how dynamic equilibria are established and allow the introduction of the concept of an equilibrium constant. Le Chtelier's principle is illustrated by further simulations. Harrison, John A.; Buckley, Paul D. J. Chem. Educ.2000, 77, 1013.

Equilibrium |

Rate Law |

Reactions

Simulations for Teaching Chemical EquilibriumPenelope A. Huddle, Margaret Dawn White, and Fiona RogersThis paper outlines a systematic approach to teaching chemical equilibrium using simulation experiments that address most known alternate conceptions in the topic. Graphs drawn using the data from the simulations are identical to those obtained using real experimental data for reactions that go to equilibrium. This allows easy mapping of the analogy to the target. Huddle, Penelope Ann; White, Margaret Dawn; Rogers, Fiona. J. Chem. Educ.2000, 77, 920.

Equilibrium |

Learning Theories

A Closer Look at Phase Diagrams for the General Chemistry CourseStephen A. GramschThe information provided by the high-pressure phase diagrams of some simple systems (carbon dioxide, water, hydrogen, and iron) can provide a useful extension to the traditional discussion of phase diagrams in the general chemistry course. At the same time, it can prepare students for a more illuminating presentation of the concept of equilibrium than is possible through the discussion of gas phase, acid-base, and solubility product equilibria alone. Gramsch, Stephen A. J. Chem. Educ.2000, 77, 718.

Equilibrium |

Phases / Phase Transitions / Diagrams |

Thermodynamics |

Geochemistry

Modeling Chemical Processes in Seawater Aquaria to Illustrate Concepts in Undergraduate ChemistryGordan GrguricThis paper describes three exercises which can be used in a variety of undergraduate chemistry curricula: (i) determining the salts and their amounts needed to prepare a given volume of artificial seawater, (ii) modeling aqueous carbonate equilibria, to calculate pH and alkalinity shifts through additions of chemicals, and (iii) modeling chemical kinetics involved in aqueous ozone-bromine reactions, to predict the type and extent of disinfection by-products. Grguric, Gordan. J. Chem. Educ.2000, 77, 495.

Aqueous Solution Chemistry |

Equilibrium |

Kinetics |

Applications of Chemistry

LeChâtelier's Principle in the SciencesVolker B. E. ThomsenThe concept of homeostasis in biology and the economic law of supply and demand are both equilibrium-like principles, but involve systems in the steady state. However, all these principles involve the stability of the system under consideration and the analogies presented may be useful in the teaching of LeChtelier's principle. Thomsen, Volker B. E. J. Chem. Educ.2000, 77, 173.

Equilibrium |

Learning Theories

An Acid-Base Chemistry Example: Conversion of NicotineJohn H. SummerfieldThe current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry.Summerfield, John H. J. Chem. Educ.1999, 76, 1397.

Graphing Calculator Strategies for Solving Chemical Equilibrium ProblemsHenry Donato Jr.A general method for finding the roots of polynomial equations using the ubiquitous and inexpensive graphing calculator is presented. It is suggested that important reactions, which are not discussed in introductory chemistry courses because of computational considerations, may now be discussed. Donato, Henry, Jr. J. Chem. Educ.1999, 76, 632.

Aqueous Solution Chemistry |

Learning Theories |

Equilibrium

Introducing Dynamic Equilibrium as an Explanatory ModelJan H. Van Driel, Wobbe de Vos, and Nico VerloopThis article describes an educational design for the introduction of chemical equilibrium, in which students' authentic experiences with chemical phenomena play a central role. The students' most effective type of reasoning appeared to be based on the idea that, in a state of equilibrium, all conditions for both the forward and the backward reaction to take place are satisfied.Van Driel, Jan H.; de Vos, Wobbe; Verloop, Nico. J. Chem. Educ.1999, 76, 559.

Equilibrium |

Learning Theories

The Complexity of Teaching and Learning Chemical EquilibriumLouise Tyson, David F. Treagust, and Robert B. BucatThis paper discusses three key issues relevant to secondary school chemistry teaching. They arise from a study of students' understanding of chemical equilibrium using qualitative and quantitative research methods. Tyson, Louise; Treagust, David F.; Bucat, Robert B. J. Chem. Educ.1999, 76, 554.

Equilibrium |

Learning Theories

Equilibrium Principles: A Game for StudentsLionel J. Edmonson Jr. and Don L. LewisThe laboratory exercise is a game using marked sugar cubes as dice. The game emphasizes the dynamic character of equilibrium. Forward and reverse rate-constant values are used to calculate an equilibrium constant and to predict equilibrium populations. Predicted equilibrium populations are compared with experimental results.Edmonson, Lionel J., Jr.; Lewis, Don L. J. Chem. Educ.1999, 76, 502.

The Fizz Keeper, a Case Study in Chemical Education, Equilibrium, and KineticsReed HowaldThe chemistry of the loss of carbonation from carbonated beverages on storage is considered. Increasing the pressure of CO2(g) will restore carbonation, but an increase in pressure adding air should not affect the equilibria. It can and does, however, affect the kinetics-the rate at which a new equilibrium is established. Thus the Fizz Keeper is effective for storage of resealed pop containers for hours, but not for periods of weeks or months. Howald, Reed. J. Chem. Educ.1999, 76, 208.

The Ksp-Solubility ConundrumRoy W. Clark and Judith M. BonicampThe authors sought to find those cases of partly soluble substances for which simple calculations such as Ksp=S2, and Ksp=4S3 can realistically be used for computing solubility from Ksp and the reverse calculation. Empirical solubility data are compared with solubilities calculated from reliable Ksp values that have been adjusted for activity coefficients. A table of 18 substances is suggested for textbook use. Clark, Roy W.; Bonicamp, Judith M. J. Chem. Educ.1998, 75, 1182.

Equilibrium: A Teaching/Learning ActivityAudrey H. WilsonThis article describes hands-on activities for high-school or undergraduate students designed to clarify important concepts involved in early studies of equilibrium. Concepts included are that at equilibrium, rate of forward reaction = rate of backward reaction; concentrations of both reactants and products remain constant; the equilibrium constant is constant at the same temperature but changes as the temperature changes; and equilibrium may be approached from different starting points. Wilson, Audrey H. J. Chem. Educ.1998, 75, 1176.

Equilibrium

"Conceptual Questions" on LeChatelier's PrincipleBenjamin P. HuddleThree "conceptual questions" presented are designed to assess the student's ability to conceptualize chemical equilibrium and to predict the effect of changes made to a system at equilibrium, using LeChatelier's principle, without doing any equilibrium constant calculations.Huddle, Benjamin P. J. Chem. Educ.1998, 75, 1175.

Formation and Dimerization of NO2 A General Chemistry ExperimentApril D. Hennis, C. Scott Highberger, and Serge Schreiner*A general chemistry experiment which illustrates Gay-Lussac's law of combining volumes. Students are able to determine the partial pressures and equilibrium constant for the formation and dimerization of NO2. The experiment readily provides students with data that can be manipulated with a common spreadsheet. Hennis, April D.; Highberger, C. Scott; Schreiner, Serge. J. Chem. Educ.1997, 74, 1340.

Why and How To Teach Acid-Base Reactions without EquilibriumTerry S. CarltonA stepwise method enables students to predict which acid-base reactions occur when two solutions are mixed. The complexities of equilibrium are avoided by treating reactions as all-or-none and by providing a table of acids in order of strength. Carlton, Terry S. J. Chem. Educ.1997, 74, 939.

Learning Theories |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Ionization or Dissociation?Emeric SchultzThe use of the terms Dissociation and Ionization in the teaching of chemistry is discussed. It is suggested that the term dissociation, and what it suggests in terms of ordinary language, is inappropriate when used in certain contexts. Since an alternate and more physically correct term, specifically ionization, is available for these contexts, it is argued that this term be used consistently in these contexts.Schultz, Emeric. J. Chem. Educ.1997, 74, 868.

Thermodynamics and SpontaneityRaymond S. OchsDespite the importance of thermodynamics as the foundation of chemistry, most students emerge from introductory courses with only a dim understanding of this subject. Ochs, Raymond S. J. Chem. Educ.1996, 73, 952.

Chemical Equilibrium in the General Chemistry CourseFainzilberg, Vladimir E.; Karp, StewartThe first chapters on chemical equilibrium in first-year college chemistry texts make an "error" in the solution of certain types of equilibria problems.Fainzilberg, Vladimir E.; Karp, Stewart J. Chem. Educ.1994, 71, 769.

Equilibrium |

Kinetics

Teaching the Truth about pHHawkes, Stephen J.-log[H+] is only an approximation to pH; how to teach pH to avoid misleading students.Hawkes, Stephen J. J. Chem. Educ.1994, 71, 747.

pH |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Fruit Anthocyanins: Colorful Sensors of Molecular MilieuCurtright, Robert D.; Rynearson, James A .; Markwell, JohnProvides background and references as a starting point for the further exploration of anthocyanins.Curtright, Robert D.; Rynearson, James A .; Markwell, John J. Chem. Educ.1994, 71, 682.

Using the Biological Cell in Teaching ElectrochemistryMerkel, Eva Gankiewicz How electricity is produced in a simple cell is correlated with how commercial batteries work; this concept can then be related to how living cells send electrical impulses.Merkel, Eva Gankiewicz J. Chem. Educ.1994, 71, 240.

Solving equilibria problems with a graphing calculator: A robust method, free of algebra and calculus Ruch, David K.; Chasteen, T. G.The method of successive approximations is frequently introduced in freshman chemistry as a means for solving equilibrium equations. However, this often requires an understanding of calculus that is problematic for introductory chemistry students. An alternative method to solving such equations is to use graphic calculators to solve problems graphically.Ruch, David K.; Chasteen, T. G. J. Chem. Educ.1993, 70, A184.

Equilibrium calculatorAllendoerfer, RobertA review of a computer program that can calculate equilibrium concentrations of all of the reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 388.

Equilibrium CalculatorAllendoerfer, RobertThe equilibrium calculator can calculate the equilibrium concentrations of all reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 126.

On the chemically impossible "other" roots in equilibrium calculations, IILudwig, Oliver G.In a previous paper the author described, using mathematics accessible to students, how an equilibrium calculation leading to a quadratic equation may be shown to have but one "chemical" root. The present work extends this demonstration to some reactions leading to cubic equations.Ludwig, Oliver G. J. Chem. Educ.1992, 69, 884.

The acid equilibrium constant is unity!Baldwin, W. G.; Burchill, C. E.The attempt to assign a non-unity value to this equilibrium constant is a consequence of misunderstanding the way in which the (nearly) constant concentration or activity of the solvent in a dilute solution (or of a pure solid or liquid in a heterogeneous system) is treated when formulating the conventional equilibrium constant expression.Baldwin, W. G.; Burchill, C. E. J. Chem. Educ.1992, 69, 514.

Acids / Bases |

Equilibrium |

Aqueous Solution Chemistry

The use of equilibrium notation in listings of standard potentials.Donkersloot, Maarten C. A.The difficulty in equilibrium notation of standard electrode potentials is due to the convention that half-reactions must be written as reductions if the given potential is to be called a (standard) electrode potential.Donkersloot, Maarten C. A. J. Chem. Educ.1992, 69, 256.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

Chemical equilibrium: I. The thermodynamic equilibrium constantGordus, Adon A.This is the first article in a series of eight that investigates the various assumptions that result in the simplified equilibrium equations found in most introductory texts. In this first article, the author considers the general nature of the constant K, Le Chatelier's principle, and the effect of the temperature on K.Gordus, Adon A. J. Chem. Educ.1991, 68, 138.

Thermodynamics |

Equilibrium

Calculating equilibrium concentrations by the continuation methodCobranchi, Daryl P.; Eyring, Edward M.The use of the continuation method allows the educator to both present more challenging equilibria to the students and to introduce students to another use for a personal computer.Cobranchi, Daryl P.; Eyring, Edward M. J. Chem. Educ.1991, 68, 40.

A small scale equilibrium experiment Flash, PatrickAn alternative method for the experiment in which the equilibrium constant for the iron-thiocyanate complex is determined.Flash, Patrick J. Chem. Educ.1990, 67, 341.

Computer simulation of chemical equilibriumCullen, John F., Jr.108. The "Great Chemical Bead Game" requires no instruments and presents the concepts of equilibrium and kinetics more clearly than an experiment. [October and November Computer Series both inadvertently called number 107. Numbering restored by skipping 109 and calling January 1990 number 110.]Cullen, John F., Jr. J. Chem. Educ.1989, 66, 1023.

Equilibrium |

Kinetics |

Rate Law

Overall chemical equationsGil, Victor M. S.An equation sum can be used safely by itself in stoichiometric and equilibrium calculations only if the intermediates produced in separate reactions are at low steady-state concentrations and if there are no other equilibria involving those species.Gil, Victor M. S. J. Chem. Educ.1989, 66, 324.

Stoichiometry |

Equilibrium

A simple explanation of the salt water oscillatorNoyes, Richard M.Yoshikawa et al. have described a simple device that undergoes repeated oscillations and that can also illustrate some of the principles essential to the oscillators driven by chemical reactions.Noyes, Richard M. J. Chem. Educ.1989, 66, 207.

Experimental work with tin(II) chloride in a high school Sanchez, Manuela MartinThe author describes a final-project performed by students that integrates concepts of hydrolysis, Le Chatelier's principle, and electrolysis. Students seek answers to questions such as: "What reactions were involved; why is an aqueous solution of SnCl2 acidic; how can elemental tin be recovered from the system?" Sanchez, Manuela Martin J. Chem. Educ.1988, 65, 898.

The perils of carbonic acid and equilibrium constantsJencks, William P.; Altura, Rachel A.It is important to remember that the small amounts of carbon dioxide that are usually present in water can have large effects on acid-base equilibria of dilute solutions and that dilute solutions of most weak acids and bases undergo significant protonation or hydrolysis when they are dissolved in water.Jencks, William P.; Altura, Rachel A. J. Chem. Educ.1988, 65, 770.

Tools of the trade Bruno, Michael J.High school teachers can never have too many visual aids when teaching chemistry. This author shares some demonstrations in equilibrium that often produce "oohs" and "aaaahs" from his students.Bruno, Michael J. J. Chem. Educ.1988, 65, 698.

Equilibrium |

pH

Some analogies for teaching rates/equilibrium Olney, David J.This article presents several analogies for teaching rates and equilibrium developed by the author over his many years in the chemistry classroom that seem to be effective.Olney, David J. J. Chem. Educ.1988, 65, 696.

VisiChemBreneman, G. L.70. Bits and pieces, 28. Many of the business spreadsheet programs can be used to answer "What if?" questions in chemistry due to the mathematical functions needed for science (such as logs, trig functions, square root) and others.Breneman, G. L. J. Chem. Educ.1986, 63, 321.

Thermodynamic changes, kinetics, equilibrium, and LeChatelier's principleHansen, Robert C.A series of demonstrations in which water in beakers and the flow of water between beakers is used to represent the components of an exothermic chemical reaction and the flow and quantity of thermal energy involved in chemical changes.Hansen, Robert C. J. Chem. Educ.1984, 61, 804.

Cooking with chemistryGrosser, Arthur E.Two demonstrations involving cooking eggs and suggestions for many more examples of cooking that illustrate important principles of chemistry. From the "State-of-the-Art Symposium for Chemical Educators: Chemistry of the Food Cycle".Grosser, Arthur E. J. Chem. Educ.1984, 61, 362.

Food Science |

Gases |

Acids / Bases |

Equilibrium |

Kinetics

NH4HC03: a stimulant for learningRichards, R. RonaldStudents, professors, and the literature have all been confused by the unusual dissociation equilibrium of NH4HCO3.Richards, R. Ronald J. Chem. Educ.1983, 60, 555.

Equilibrium |

Amines / Ammonium Compounds |

Gases

On the chemically impossible "other" roots in equilibrium problemsLudwig, Oliver G.Students often have a hard time knowing when to disregard equilibrium roots that are too large or are negative. The author suggests a convincing proof that helps students understand how the relationship between the conceptual and mathematical.Ludwig, Oliver G. J. Chem. Educ.1983, 60, 547.

Le Châtelier's principle: the effect of temperature on the solubility of solids in liquidsBrice, L. K.The purpose of this article is to provide a rigorous but straightforward thermodynamic treatment of the temperature dependence of solubility of solids in liquids that is suitable for presentation at the undergraduate level. The present discussion may suggest how to approach the qualitative aspects of the subject for freshman.Brice, L. K. J. Chem. Educ.1983, 60, 387.

A chemistry lesson at Three Mile IslandMammano, Nicholas J.Teaching principles of general chemistry through references made to the nuclear incident at Three Mile Island.Mammano, Nicholas J. J. Chem. Educ.1980, 57, 286.

Equilibrium |

Gases |

Stoichiometry |

Nonmajor Courses |

Nuclear / Radiochemistry |

Applications of Chemistry

"To sink or swim"O'Connor, RodA problem regarding the maximum water hardness that can be permitted in a swimming pool if it is desired to avoid calcite formation given the carbonate ion concentration. [Debut]O'Connor, Rod J. Chem. Educ.1980, 57, 151.

Strong and weak acids and basesDeck, Joseph C.The designations "strong" and "weak" are used in various ways, and often with respect to the same compound in different situations.Deck, Joseph C. J. Chem. Educ.1979, 56, 814.

The temperature dependence of the equilibrium constantBurness, James H.This exam question tests a student's ability to derive the temperature dependence of an equilibrium constant not by qualitatively applying Le Chatelier's principle, but by understanding the relationship between the kinetics of the equation and the value of Keq.Burness, James H. J. Chem. Educ.1979, 56, 395.

Intuitive and general approach to acid-base equilibrium calculationsFelty, Wayne L.The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.Felty, Wayne L. J. Chem. Educ.1978, 55, 576.

Acids / Bases |

Equilibrium |

Chemometrics

Temperature dependence of Kw Steffel, M. J.The question presented in this note requires the resolution of a conflict between a common sense notion and an isolated fact.Steffel, M. J. J. Chem. Educ.1978, 55, 243.

Simultaneous equilibria involving insoluble saltsBaumann, Jacob B.This demonstration is derived from and involves the same reactions as the Mohr titration of chloride ion with silver nitrate solution using potassium chromate as an indicator.Baumann, Jacob B. J. Chem. Educ.1977, 54, 618.

Equilibrium |

Precipitation / Solubility |

Aqueous Solution Chemistry

Water dipping kinetics. A physical analog for chemical kineticsBirk, James P.; Gunter, S. KayPhysical analogs of zero-, first, and second-order kinetics using the volume of water transferred by a dipper oriented in different directions with respect to a basin of water.Birk, James P.; Gunter, S. Kay J. Chem. Educ.1977, 54, 557.

Effect of Ionic Strength on Equilibrium ConstantsSeymour, M. D.; Fernando, QuintusInvolves the determination of the acid dissociation constant of bromcresol green by a spectrophotometric method; using a graphing calculator, each student can perform the laboratory work and obtain his own data set.Seymour, M. D.; Fernando, Quintus J. Chem. Educ.1977, 54, 225.

Maximizing profits in equilibrium processesRish, Ronald J.Provides the student with an example in which both chemical principles and calculus are applied to a realistic industrial situation where profits are a must.Rish, Ronald J. J. Chem. Educ.1975, 52, 441.

Molar solubility calculations and the control equilibriumChaston, S. H. H.The Control-Equilibrium method uses as its starting point a precise procedure for obtaining the equilibrium that accounts for the bulk of the decomposition of starting materials.Chaston, S. H. H. J. Chem. Educ.1975, 52, 206.

Physical chemistry of the drinking duckPlumb, Robert C.; Wagner, Robert E.The operation of the drinking bird is easily understood in terms of a few elementary physical chemistry principles.Plumb, Robert C.; Wagner, Robert E. J. Chem. Educ.1973, 50, 213.

The design and use of an equilibrium machineAlden, Robert T.; Schmuckler, Joseph S.An operating model that can be used to determine quantitatively equilibrium shifts when demonstrating Le Chatelier's Principle and relates to molecular level considerations and the probabilistic nature of equilibrium.Alden, Robert T.; Schmuckler, Joseph S. J. Chem. Educ.1972, 49, 509.

MiscellaneousAlyea, Hubert N.These twelve overhead projection demonstrations include rates of reactions, clock reactions, the effect of temperature and the presence of a catalyst on the decomposition of hydrogen peroxide, the relationship between viscosity and temperature, equilibria, solubility product, and the common ion effect.Alyea, Hubert N. J. Chem. Educ.1970, 47, A437.

Prolonging death (in apples)Plumb, Robert C.Using controlled atmosphere storage to prolong the freshness of vegetables and fruits after they have been harvested.Plumb, Robert C. J. Chem. Educ.1970, 47, 518.

Equilibrium |

Kinetics |

Agricultural Chemistry |

Applications of Chemistry |

Gases

The use of specific ion electrodes for equilibrium measurementsWilliams, T. R.; Boettner, Wayne; Wakeham, StuartThe purpose of this investigation is to suggest the variety of information that can be obtained using specific ion electrodes.Williams, T. R.; Boettner, Wayne; Wakeham, Stuart J. Chem. Educ.1970, 47, 464.

Ion Selective Electrodes |

Equilibrium

Sealed tube experimentsCampbell, J. A.Lists and briefly describes a large set of "sealed tube experiments," each of which requires less than five minutes to set-up and clean-up, requires less than five minutes to run, provides dramatic results observable by a large class, and illustrates important chemical concepts.Campbell, J. A. J. Chem. Educ.1970, 47, 273.

The law of mass actionBerline, Steven; Bricker, ClarkIt is the purpose of this paper to present a derivation of the Law of Mass Action that should have meaning and could be used at an elementary level.Berline, Steven; Bricker, Clark J. Chem. Educ.1969, 46, 499.

From stoichiometry and rate law to mechanismEdwards, John O.; Greene, Edward F.; Ross, JohnExamines the rules used by chemists as guidelines in developing mechanisms from stoichiometric and rate law observations. Edwards, John O.; Greene, Edward F.; Ross, John J. Chem. Educ.1968, 45, 381.

Teaching ionic equilibrium: Use of log chart transparenciesFreiser, Henry; Fernando, QuintusThe use of graphical methods brings the problem of significance of various terms in complicated expressions into proper focus. Furthermore, a pictorial representation permits the student to see at a glance how the concentrations of various species in a system at equilibrium change with conditions.Freiser, Henry; Fernando, Quintus J. Chem. Educ.1965, 42, 35.

Equilibria in ionic solutionsKokes, R. J.; Dorfman, M. K.; Mathia, T.In conjunction with lectures on equilibria in electrolytic solutions, students perform a set of laboratory experiments in which they determine both the ionization constant of chloroacetic acid and the solubility of its silver salt.Kokes, R. J.; Dorfman, M. K.; Mathia, T. J. Chem. Educ.1962, 39, 93.

The equilibria of complex formationBanks, James E.Despite the present recognition of the stepwise formation of complexes in solution, many textbooks continue to treat it as a one-step process, presumably to preserve a reasonable simplicity in the mathematical computation of concentrations.Banks, James E. J. Chem. Educ.1961, 38, 391.

Equilibrium |

Coordination Compounds |

Aqueous Solution Chemistry

An approach to complex equilibrium problemsButler, James N.Presents an approach to equilibrium problems that sets up enough equations relating the various concentrations present to define the system completely and then makes approximations that simplify the equations.Butler, James N. J. Chem. Educ.1961, 38, 141.

Potentiometric measurements of equilibria: In general chemistry laboratoryChesick, J. P.; Patterson, Andrew, Jr.The authors describe an experiment in which the solubility product of silver chloride, the ionization constant of the silver-ammonia complex, and the ionization constant of acetic acid can be determined with one afternoon of work.Chesick, J. P.; Patterson, Andrew, Jr. J. Chem. Educ.1959, 36, 496.

The analyst and the inconstant constantsRingbom, AndersSimple theories taught to freshmen often do not agree well with experimental data; the author examines the case of equilibrium constants and elaborates on a method of dealing with this problem.Ringbom, Anders J. Chem. Educ.1958, 35, 282.

Le Châtelier's principle and the equilibrium constantMiller, Arild J.Many students of chemistry have difficulty in understanding how the position of equilibrium in a gaseous reaction can change when the pressure is altered, in accordance with Le Châtelier's principle, without causing a corresponding variation in the equilibrium constant.Miller, Arild J. J. Chem. Educ.1954, 31, 455.

Equilibrium |

Reactions |

Gases

Solubility of silver salts in aqua ammoniaJohnson, Clyde R.Examines two problems regarding the calculation of the solubility of a silver salt in aqua ammonia of a given concentration.Johnson, Clyde R. J. Chem. Educ.1954, 31, 205.

Precipitation / Solubility |

Equilibrium

Praseodymium tetrafluoridePerros, Theodore P.; Munson, Thomas R.; Naeser, Charles R.In spite of the experimental failures to prepare praseodymium tetrafluoride, there is strong evidence for its possible formation to be found by calculating the equilibrium constants for some of the reactions by which this compound might be prepared.Perros, Theodore P.; Munson, Thomas R.; Naeser, Charles R. J. Chem. Educ.1953, 30, 402.

A temperature-equilibrium demonstrationBrown, John A.This demonstration makes use of the colored cobaltous complexes in a mixed solvent to show the dependence of some equilibria on temperature.Brown, John A. J. Chem. Educ.1951, 28, 640.